Magnetic recording medium fabrication method

ABSTRACT

A method of fabricating a magnetic recording medium by sequentially forming a magnetic recording layer, a protection layer, and a lubricant layer on a stacked body, includes forming the lubricant by depositing a first lubricant on the stacked body after forming the protection layer, by vapor-phase lubrication deposition, without exposing the stacked body to atmosphere, and depositing a second lubricant on the stacked body after depositing the first lubricant, by vapor-phase lubrication deposition, without exposing the stacked body to atmosphere. The first lubricant has a lower molecular mass and a higher chemical polarity than those of the second lubricant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/217,637 filed on Mar. 18, 2014, which is based upon andclaims the benefit of priority of the prior Japanese Patent ApplicationNo. 2013-076959 filed on Apr. 2, 2013, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic recording medium fabricationmethod.

2. Description of the Related Art

Recently, a magnetic storage apparatus may be provided in variousproducts, including a personal computer, a video recorder, a dataserver, and the like, and the importance of the magnetic storageapparatus is increasing. The magnetic storage apparatus includes amagnetic recording medium that magnetically stores electronic data bymagnetic recording. Examples of the magnetic storage apparatus include amagnetic disk drive, a flexible disk drive, a magnetic tape apparatus,and the like. A HDD (Hard Disk Drive) is an example of the magnetic diskdrive.

For example, a general magnetic recording medium has a multi-layerstacked structure including an underlayer, an intermediate layer, amagnetic recording layer, and a protection layer that are deposited inthis sequence on a nonmagnetic substrate, and a lubricant layer coatedon a surface of the protection layer. In order to prevent mixing ofimpurities between the layers forming the magnetic recording mediumduring fabrication of the magnetic recording medium, an in-line vacuumdeposition apparatus is used to continuously stack the layers underdecompression, as described in Japanese Laid-Open Patent Publication No.8-274142, for example.

In the in-line vacuum deposition apparatus, a plurality of depositionchambers having a deposition means capable of depositing a layer on thesubstrate are connected via a gate valve, together with a chamber forcarrying out a thermal process and an auxiliary chamber, are provided inorder to form a single deposition line. When the substrate is set on acarrier and passes through the deposition line, the layers aresuccessively deposited on the substrate to fabricate the magneticrecording medium having the desired structure.

Generally, the deposition line is arranged in a ring shape, and asubstrate loading and unloading chamber is provided in the depositionline in order to load and unload the substrate with respect to thecarrier. The carrier, which passes through the deposition chambers ofthe deposition line, reaches the substrate loading and unloading chamberwhere the substrate having the layers deposited thereon is unloaded fromthe carrier. In addition, after removing the substrate from the carrier,a new substrate to be subjected to the deposition is loaded onto thecarrier in the substrate loading and unloading chamber.

In addition, as a method of forming the lubricant layer on the surfaceof the magnetic recording medium, a vapor-phase lubrication has beenproposed in Japanese Laid-Open Patent Publication No. 2004-002971, forexample. The vapor-phase lubrication places the magnetic recordingmedium within a vacuum chamber, and introduces gas lubricant into thevacuum chamber.

In addition, a magnetic recording medium having a lubricant layer formedby two layers has been proposed in Japanese Laid-Open Patent PublicationNo. 2006-147012, for example. The lubricant layer of this proposedmagnetic recording medium is formed by a fixing layer (or bond layer)that is provided on the side of the protection layer, is chemicallystable, and has a suitable bond with respect to the protection layer,and a fluid (or free layer) that is provided on the surface side of themagnetic recording medium and is mainly made of a material having a lowcoefficient of friction.

Furthermore, forming the protection layer from carbon nitride andforming the lubricant layer from perfluoropolyether that includes aterminal group having an amine structure, in order to increase thebonded ratio between the protection layer and the lubricant layer to 70%or higher, has been proposed in Japanese Laid-Open Patent PublicationNo. 2000-222719, for example. The bonded ratio is measured by dippingthe magnetic recording medium formed with the lubricant layer in afluorocarbon solvent for five (5) minutes while applying ultrasonicwaves, and measuring the absorbance in a vicinity of 1270 cm⁻¹ at thesame position on the same medium before and after the dipping using ESCA(Electron Spectroscopy for Chemical Analysis). The bonded ratio isdefined as a percentage of the ratio of the absorbances before and afterthe dipping, using a formula [{(Absorbance After Dipping)/(AbsorbanceBefore Dipping)}×100].

When the contact between the magnetic recording medium and the magnetichead is taken into consideration, the coefficient of friction of thelubricant layer is preferably low. On the other hand, when a corrosionresistance of the magnetic recording medium is taken into consideration,a coverage of the surface of the protection layer provided by thelubricant layer is preferably high.

SUMMARY OF THE INVENTION

Embodiments of the present invention may provide magnetic recordingmedium fabrication method that can simultaneously obtain a lowcoefficient of friction of the lubricant layer and a high coverage ofthe surface of the protection layer by the lubricant layer.

According to one aspect of the present invention, a method offabricating a magnetic recording medium by sequentially forming amagnetic recording layer, a protection layer, and a lubricant layer on astacked body, includes forming the lubricant layer, wherein the formingthe lubricant layer includes depositing a first lubricant on the stackedbody after forming the protection layer, by vapor-phase lubricationdeposition, without exposing the stacked body to atmosphere; anddepositing a second lubricant on the stacked body after depositing thefirst lubricant, by vapor-phase lubrication deposition, without exposingthe stacked body to atmosphere, wherein the first lubricant has amolecular mass lower than a molecular mass of the second lubricant, andwherein the first lubricant has a chemical polarity higher than achemical polarity of the second lubricant.

According to another aspect of the present invention, a method offabricating a magnetic recording medium by sequentially forming amagnetic recording layer, a protection layer, and a lubricant layer on astacked body, includes forming the lubricant layer, wherein the formingthe lubricant layer includes depositing a first lubricant on the stackedbody after forming the protection layer, by vapor-phase lubricationdeposition, without exposing the stacked body to atmosphere; anddepositing a second lubricant on the stacked body after depositing thefirst lubricant, by vapor-phase lubrication deposition, without exposingthe stacked body to atmosphere, wherein the first lubricant has amolecular mass higher than a molecular mass of the second lubricant,wherein the first lubricant has a chemical polarity lower than achemical polarity of the second lubricant, and wherein the depositingthe second lubricant substitutes the first lubricant in part or in itsentirety by the second lubricant.

Other objects and further features of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an example of a magneticrecording medium fabrication apparatus in one embodiment of the presentinvention;

FIG. 2 is a cross sectional view illustrating an example of a magneticrecording medium fabricated by the fabrication apparatus illustrated inFIG. 1; and

FIG. 3 is a perspective view illustrating an example of a configurationof a magnetic storage apparatus having the magnetic recording mediumfabricated in one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will be given of the magnetic recording medium fabricationmethod in each embodiment of the present invention, by referring to thedrawings.

According to studies conducted by the present inventors, when theprocesses to form the magnetic recording layer up to the lubricant layerof the magnetic recording medium are carried out continuously withoutexposing the stacked body to the atmosphere (or non-enclosed environmentopen to air), it was found that a ratio (or bonded ratio) of the bondlayer included in the lubricant layer may be made close to 100%depending on the kind of lubricant that is used. However, according tostudies conducted by the present inventors, the 100% bonded ratio of thelubricant layer is not always the optimum value. From the standpoint ofreducing the coefficient of friction when the magnetic recording mediumand the magnetic head make contact, the lubricant layer preferablyincludes a suitable free layer. On the other hand, from the standpointof increasing the corrosion resistance of the magnetic recording medium,the coverage of the surface of the protection layer provided by thelubricant layer is preferably high.

Hence, as will be described hereunder, the present inventors haveconceived a magnetic recording medium fabrication method and a magneticrecording medium fabrication apparatus that increase the bonded ratio ofthe lubricant layer with respect to the surface of the protection layerwithin an appropriate range, in order to include a suitable free layerin the lubricant layer and to increase the coverage of the surface ofthe protection layer provided by the lubricant layer, simultaneously.

The lubricant layer of the magnetic recording medium is required to havea chemically stable bond layer with a strong bond (that is, a highbonded ratio) with respect to the protection layer on the side of theprotection layer, and a free layer mainly made of a material having alow coefficient of friction on the surface side of the magneticrecording medium. In other words, the lubricant layer includes the bondlayer provided on the protection layer, and the free layer provided onthe bond layer. The bond layer may be formed with ease using thevapor-phase lubrication deposition. However, it may be difficult toincrease the coverage of the surface of the protection layer provided bythe lubricant, and to include a suitable free layer in the lubricantlayer, simultaneously. In other words, the lubricant layer of themagnetic recording medium having such characteristics is in many casesformed using a special lubricant or a mixture of special lubricants,however, such special lubricants are difficult to deposit using thevapor-phase lubrication deposition. In other words, only compoundshaving a low molecular mass and a low boiling point may be vaporized anddeposited first. In addition, when a heating temperature is set high inorder to simultaneously vaporize the compounds, decomposition or thermalpolymerization of a part of the compounds included in the lubricant mayoccur, to transform such parts into another compound.

On the other hand, in the magnetic recording medium fabrication methodin each embodiment, a first lubricant is deposited on the stacked bodyusing the vapor-phase lubrication deposition, and a second lubricant isthereafter deposited on the stacked body using the vapor-phaselubrication deposition. Hence, it is possible to form a lubricant layerthat includes the bond layer and the free layer to suitable extents.

In addition, in the magnetic recording medium fabrication method in afirst embodiment, the first lubricant preferably has a molecular masslower than a molecular mass of the second lubricant, and a chemicalpolarity higher than a chemical polarity of the second lubricant. Whenthe lubricant layer is formed by depositing the lubricant having thelower molecular mass by the vapor-phase lubrication deposition, thecoverage of the protection layer provided by the lubricant layer can beincreased. The increased coverage may be provided by the lubricanthaving the lower molecular mass, because the lubricant having the lowermolecular mass has shorter polymer chains and may be uniformlydistributed with ease on the surface of the protection layer, ascompared to the lubricant having the higher molecular mass having longerpolymer chains that may tangle and easily form meshes such that regionsnot covered by the lubricant are likely generated on the surface of theprotection layer. Further, when the chemical polarity of the firstlubricant is higher than that of the second lubricant, a high bondedratio can be obtained with respect to the surface of the protectionlayer. Hence, in a case in which the first lubricant having the lowermolecular mass is deposited on the stacked body by the vapor-phaselubrication deposition, it is easier to form a bond layer having a highbonded ratio and a high coverage with respect to the surface of theprotection layer, and the corrosion resistance of the magnetic recordingmedium can be improved.

In the magnetic recording medium fabrication method in the firstembodiment, the second lubricant preferably has a molecular mass higherthan the molecular mass of the first lubricant, and a chemical polaritylower than the chemical polarity of the first lubricant. The secondlubricant may mainly function as a free layer in the lubricant layer.Hence, when the molecular mass of the second lubricant is high, thethermal stability increases and a low coefficient of friction can beobtained with respect to the magnetic head even when the magneticrecording medium is used under a high temperature environment, and ahighly reliable magnetic recording medium can be fabricated. Inaddition, when the chemical polarity of the second lubricant is lowerthan that of the first lubricant, a phenomenon (hereinafter alsoreferred to as “lubricant pickup” of the magnetic head or head slider)in which the lubricant of the free layer adheres onto the magnetic head(or head slider) can be reduced.

In the magnetic recording medium fabrication method in the firstembodiment, the first lubricant is preferably a tetraol having amolecular mass in a range of 500 to 2000. By using such a compound forthe first lubricant, the coverage of the surface of the stacked bodyprovided by the first lubricant can be increased. Tetraol is a genericname for an aliphatic compound or an alicyclic compound in which four(4) hydroxyl groups are bonded to four (4) different carbons, and mayinclude the following compound, for example. In the following formula, pand q denote integers, and the number average molecular mass is 500 to2000.

Moreover, in the magnetic recording medium fabrication method in thefirst embodiment, the second lubricant is preferably a diol having amolecular mass in a range of 1500 to 5000. Such a compound is thermallystable, and a low coefficient of friction is easily obtained withrespect to the magnetic head even when the magnetic recording medium isused under a high temperature environment. Diol is a generic name for analiphatic compound or an alicyclic compound in which two (2) hydroxylgroups are bonded to two (2) different carbons, and may include thefollowing compound, for example. In the following formula, p and qdenote integers, and the number average molecular mass is 1500 to 5000.In a case in which the second lubricant includes diol, the chemicalpolarity of the lubricant can be adjusted by an amount of hydroxylgroups. In the first embodiment, the chemical polarity of the firstlubricant (for example, tetraol) is adjusted to be higher than thechemical polarity of the second lubricant (for example, diol).HOCH₂—CF₂O—(CF₂CF₂O)_(p)—(CF₂O)_(q)—CF₂—CH₂OH

In the magnetic recording medium fabrication method in the firstembodiment, the second lubricant may be at least one of the lubricantsrepresented by the following formulas (1) through (3), used in place ofthe diol, or in combination with the diol by mixing the lubricants tothe diol. These lubricants have a high thermal stability, and a lowcoefficient of friction can be obtained with respect to the magnetichead even when the magnetic recording medium is used under a hightemperature environment. When mixing these lubricants for use as thesecond lubricant, the vapor pressure at the time of deposition of eachof the lubricants is preferably set to the same pressure, so that eachof the lubricants is included evenly within the process gas of thevapor-phase lubrication deposition.

In the generalized formula (1) above, x is an integer from 1 to 5, R₁denotes one of a hydrogen atom, alkyl group having 1 to 4 carbons, orhalogenated alkyl group having 1 to 4 carbons, and R₂ denotes asubstituent of an end group —CH₂OH or —CH(OH)CH₂OH. In the generalizedformula (2) above, n is an integer in a range of 4 to 36. In thegeneralized formula (3), a, b, c, d are integers in a range of 4 to 40.

On the other hand, in the magnetic recording medium fabrication methodin a second embodiment, the first lubricant has a molecular mass higherthan that of the second lubricant, and a chemical polarity lower thanthat of the second lubricant. In other words, the second lubricant has amolecular mass lower than that of the first lubricant, and a chemicalpolarity higher than that of the first lubricant. Further, a process offorming the second lubricant on the stacked body may be a process ofsubstituting a part of or the entire first lubricant deposited on thestacked body by the second lubricant, that is, substituting the firstlubricant in part or in its entirety by the second lubricant. Byemploying such a method of fabrication, it is possible to fabricate amagnetic recording medium having a configuration similar to that of themagnetic recording medium fabricated in the first embodiment.Consequently, it is possible to increase the coverage of the protectionlayer provided by the lubricant layer, increase the thermal stability ofthe free layer, and obtain a low coefficient of friction with respect tothe magnetic head even when the magnetic recording medium is used undera high temperature environment, to thereby provide a highly reliablemagnetic recording medium.

Moreover, in the magnetic recording medium fabrication method in thesecond embodiment, the first lubricant is preferably a diol having amolecular mass in a range of 1500 to 5000. By using such a compound forthe first lubricant, the coverage of the surface of the stacked bodyprovided by the first lubricant can be increased. Diol is a generic namefor an aliphatic compound or an alicyclic compound in which two (2)hydroxyl groups are bonded to two (2) different carbons, and may includethe following compound, for example. In a case in which the firstlubricant includes diol, the chemical polarity of the diol can beadjusted by the amount of hydroxyl groups. In the following formula, pand q denote integers, and the number average molecular mass is 1500 to5000.HOCH₂—CF₂O—(CF₂CF₂O)_(p)—(CF₂O₂)_(q)—CF₂—CH₂OH

In the magnetic recording medium fabrication method in the secondembodiment, the second lubricant is preferably a tetraol having amolecular mass in a range of 500 to 2000. Such a compound is thermallystable, and a low coefficient of friction is easily obtained withrespect to the magnetic head even when the magnetic recording medium isused under a high temperature environment. Tetraol is a generic name foran aliphatic compound or an alicyclic compound in which four (4)hydroxyl groups are bonded to four (4) different carbons, and mayinclude the following compound, for example. In a case in which thesecond lubricant includes tetraol, the chemical polarity of the tetraolcan be adjusted by the amount of hydroxyl groups. In the followingformula, p and q denote integers, and the number average molecular massis 500 to 2000.

In the magnetic recording medium fabrication method in the secondembodiment, the second lubricant may be at least one of the lubricantsrepresented by the following formulas (4) through (6), used in place ofthe tetraol, or in combination with the tetraol by mixing the lubricantsto the tetraol. These lubricants have a high thermal stability, and alow coefficient of friction can be obtained with respect to the magnetichead even when the magnetic recording medium is used under a hightemperature environment. When mixing these lubricants for use as thesecond lubricant, the vapor pressure at the time of deposition of eachof the lubricants is preferably set to the same pressure, so that eachof the lubricants is included evenly within the process gas of thevapor-phase lubrication deposition.

In the generalized formula (4) above, x is an integer from 1 to 5, R₁denotes one of a hydrogen atom, alkyl group having 1 to 4 carbons, orhalogenated alkyl group having 1 to 4 carbons, and R₂ denotes asubstituent of an end group —CH₂OH or —CH(OH)CH₂OH. In the generalizedformula (5) above, n is an integer in a range of 4 to 36. In thegeneralized formula (6), a, b, c, d are integers in a range of 4 to 40.

In the magnetic recording medium fabrication method in each embodiment,the surface of the protection layer is preferably subjected to nitridingor oxidizing, after the formation of the protection layer and before thedeposition of the first lubricant on the stacked body. In addition, theprotection layer, or a surface layer portion after the formation of theprotection layer is preferably formed by carbon nitride or carbon oxide.

According to studies conducted by the present inventors, when purecarbon is used for the protection layer and the lubricant layer isformed by the vapor-phase lubrication deposition employed by themagnetic recording medium fabrication method in each embodiment, it wasfound that the bonded ratio of the bond layer included in the lubricantlayer may be made close to 100%. However, according to studies conductedby the present inventors, the 100% bonded ratio of the lubricant layeris not always the optimum value, and the lubricant layer preferablyincludes a suitable free layer. Hence, in the magnetic recording mediumfabrication method in each embodiment, the surface of the protectionlayer is subjected to nitriding or oxidizing, or the protection layer orthe surface layer portion after the formation of the protection layer isformed by carbon nitride or carbon oxide. As a result, the bonded ratioof the bond layer (mainly the layer formed by the first lubricant)included in the lubricant layer is set lower than 100%, and the freelayer (mainly the layer formed by the second lubricant) is bonded on thesurface of the protection layer. Consequently, the low coefficient offriction of the free layer with respect to the magnetic head can bemaintained, while reducing the lubricant pickup. When the lubricantpickup occurs, it is well known that the coefficient of friction of thehead slider increases to thereby make a stable operation of the HDDdifficult.

In the magnetic recording medium fabrication method in each embodiment,known methods may be employed to subject the surface of the protectionlayer to nitriding or oxidizing, or to form the protection layer or thesurface layer portion after the formation of the protection layer bycarbon nitride or carbon oxide. For example, the known methods includeinjecting nitrogen atoms or oxygen atoms onto the surface of theprotection layer, introducing nitrogen gas or oxygen gas into a reactionchamber during the deposition process to deposit the protection layer orat a final stage of the deposition process.

In the magnetic recording medium fabrication method in each embodiment,the bonded ratio between the protection layer and the first lubricant ispreferably in a range of 60% to 90%. By setting the bonded ratio betweenthe protection layer and the first lubricant within such a range, asuitable bond can be obtained between the free layer formed by thesecond lubricant and the surface of the protection layer. In themagnetic recording medium fabrication method in each embodiment, thebonded ratio between the protection layer and the second lubricant ispreferably in a range of 10% to 30%.

The bonded ratio may be measured by dipping the magnetic recordingmedium formed with the lubricant layer in a fluorocarbon solvent forfive (5) minutes, and measuring the absorbance in a vicinity of 1270cm⁻¹ at the same position on the same medium before and after thedipping using ESCA (Electron Spectroscopy for Chemical Analysis). Thebonded ratio may be defined as a percentage of the ratio of theabsorbances before and after the dipping, that is, by [{(AbsorbanceAfter Dipping)/(Absorbance Before Dipping)}×100]. For example, thefluorocarbon solvent may be Vertrel XF manufactured by Du Pont-MitsuiFluorochemicals Co., Ltd., or other similar products.

In the magnetic recording medium fabrication method in each embodiment,a first process chamber in which the first lubricant is deposited on thestacked body by the vapor-phase lubrication, a second process chamber inwhich the second lubricant is deposited on the stacked body by thevapor-phase lubrication, and a transport region between the first andsecond process chambers to transport the stacked body, may be provided.In a case in which the first process chamber has a process gas pressureA, the second process chamber has a process gas pressure B, and thetransport region has a gas pressure C, relationships C>A and C>B arepreferably satisfied.

Next, a description will be given of an example of the magneticrecording medium fabrication method that forms the magnetic recordinglayer, the protection layer, and the lubricant layer in this sequence onthe stacked body.

FIG. 1 is a schematic diagram illustrating an example of the magneticrecording medium fabrication apparatus in one embodiment of the presentinvention. The magnetic recording medium fabrication apparatusillustrated in FIG. 1 may include a deposition apparatus 101 configuredto form the layers of the magnetic recording medium up to the protectionlayer, and a vapor-phase lubrication deposition apparatus 102 configuredto form the lubricant layer on the surface of the protection layer.

The deposition apparatus 101 may include a substrate loading andunloading chamber 903, a first corner chamber 904, a first processchamber 905, a second process chamber 906, a second corner chamber 907,a third process chamber 908, a fourth process chamber 909, a fifthprocess chamber 910, a sixth process chamber 911, a seventh processchamber 912, an eighth process chamber 913, a third corner chamber 914,a ninth process chamber 915, a tenth process chamber 916, a fourthcorner chamber 917, eleventh and twelfth process chambers 918 and 919 toform the protection layer, a thirteenth process chamber 920 to injectnitrogen atoms or oxygen atoms onto the surface of the protection layer,and an auxiliary chamber 921 that are connected in a ring shape viainter-chamber gate valves G. Each of the chambers 903 through 921 issurrounded by a plurality of partitioning walls, and includes aninternal space that may be put into a decompression state.

The inter-chamber gate valve G, which may freely open and close at ahigh speed, may be provided between two mutually adjacent chambers (forexample, the chambers 905 and 906). All of the gate valves G are openedand closed at the same timing. Hence, each of a plurality of carriers925 that transport substrates (not illustrated) may move from one to theother of the mutually adjacent chambers with regularity.

Each of the first through thirteenth process chambers 905, 906, 908through 913, 915, 916, and 918 through 920 may be provided with asubstrate heating means (or substrate heater), a deposition means (ordeposition part), a process gas supplying means (or process gassupplying part), processing means, an exhaust means (or exhaust part),and the like. The deposition means may be formed by a sputteringapparatus, an ion beam deposition apparatus, or the like. The gassupplying means and the exhaust means may cause the process gas to flowwhen necessary.

For example, the first process chamber 905 to the tenth process chamber916 may be used to form the magnetic recording layer of the magneticrecording medium, and the eleventh and twelfth process chambers 918 and919 may be used to form the protection layer. In this example, thenitrogen atoms or the oxygen atoms are injected onto the surface of theprotection layer in the thirteenth process chamber 920. Moreparticularly, nitrogen gas or oxygen gas is ionized by plasma, and theions are accelerated by a high voltage to be injected onto the surfaceof the protection layer.

A base pressure (or reaching pressure) of each of the first throughthirteenth process chambers 905, 906, 908 through 913, 915, 916, and 918through 920 may be set to 1×10⁻⁵ Pa, for example.

The corner chambers 904, 907, 914, and 917 may be arranged at corners ofthe magnetic recording medium deposition apparatus 101, and change theorientation of the carrier 925 in accordance with a moving direction ofthe carrier 925. The inside of each of the corner chambers 904, 907,914, and 917 may be set to high vacuum, and each of the corner chambers904, 907, 914, and 917 may rotate the carrier 925 in a decompressionstate.

As illustrated in FIG. 1, the substrate loading and unloading chamber903 is arranged between the first corner chamber 904 and the auxiliarychamber 921. The internal space of the substrate loading and unloadingchamber 903 may be larger than that of other chambers. Two (2) carriers925 may be arranged within the substrate loading and unloading chamber903, such that the substrate is loaded onto one carrier 925 and thesubstrate is unloaded from another carrier 925. Each of the carriers 925may be transported simultaneously in a direction indicated by arrows inFIG. 1. The substrate loading and unloading chamber 903 may be connectedto a substrate input chamber 902 and a substrate output chamber 922.

A vacuum robot 111 may be arranged within the substrate input chamber902, and another vacuum robot 112 may be arranged within the substrateoutput chamber 922. The vacuum robots 111 and 112 are examples of atransport apparatus. The substrate input chamber 902 may load thesubstrate onto the carrier 925 within the substrate loading andunloading chamber 903, using the vacuum robot 111. In addition, thesubstrate output chamber 922 may unload the substrate from the carrier925 within the substrate loading and unloading chamber 903, using thevacuum robot 112.

The substrate input chamber 902 may be connected to an airlock chamber12 via an inter-chamber gate valve G2. The substrate output chamber 922may be connected to an airlock chamber 13 via an inter-chamber gatevalve G3. A plurality of substrates (for example, 50 substrates) may beaccommodated within each of the airlock chambers 12 and 13. Each of theairlock chambers 12 and 13 may have a function to exchange theaccommodated substrates at both ends of the chamber. The operation ofeach of the airlock chambers 12 and 13 may be a repetition of theprocess described hereunder.

(Input of Substrate to Deposition Apparatus)

The input of the substrate to the deposition apparatus 101 may becarried out by the process including the following steps s1 through s8.

Step s1: Gate values G1 and G2 are closed.

Step s2: The inside of the airlock chamber 12 is set to atmosphericpressure.

Step s3: The gate valve G1 is opened.

Step s4: The plurality of substrates (for example, 50 substrates) areinput to the airlock chamber 12 by a substrate input robot 940 which isan example of a transport apparatus.

Step s5: The gate valve G1 is closed.

Step s6: The inside of the airlock chamber 12 is decompressed to vacuum.

Step s7: The gate valve G2 is opened.

Step s8: The substrate within the airlock chamber 12 is loaded onto thecarrier 925 within the substrate loading and unloading chamber 903 bythe vacuum robot 111.

(Output of Stacked Body from Deposition Apparatus and Input of StackedBody to Vapor-Phase Lubrication Deposition Apparatus)

The output of the stacked body from the deposition apparatus 101 and theinput of the stacked body to the vapor-phase lubrication depositionapparatus 102 may be carried out by the process including the followingsteps s11 through s18.

Step s11: The gate valves G3 and G4 are closed.

Step s12: The inside of the airlock chamber 13 is decompressed tovacuum.

Step s13: The gate valve G3 is opened.

Step s14: The substrate is removed from the carrier 925 within thesubstrate loading and unloading chamber 903, and set within the airlockchamber 12, using the vacuum robot 112.

Step s15: The gate valve G3 is closed when the inside of the airlockchamber 12 becomes full of substrates (for example, 50 substrates areset).

Step s16: The inside of the airlock chamber 13 is decompressed tovacuum.

Step s17: The gate valve G4 is opened.

Step s18: The substrates (for example, 50 substrates) within the airlockchamber 12 are input to the vapor-phase lubrication deposition apparatus102 using a vacuum robot 941 provided within a vacuum container 942. Thevacuum robot 941 is an example of a transport apparatus.

Returning now to the description of FIG. 1, the vapor-phase lubricationdeposition apparatus 102 may include the isolation chamber 943 to befilled with the inert gas, a vapor-phase lubrication process chamber 944a which is an example of the first process chamber in which the firstlubricant is deposited on the stacked body, a vapor-phase lubricationprocess chamber 944 c which is an example of the second process chamberin which the second lubricant is deposited on the stacked body, aseparation chamber 944 b which is an example of the process chamberprovided between the first and second process chambers, an airlockchamber 945, and a transport cassette return path chamber 947 that areconnected via gate valves G6, G11, G12, G7, G9, and G10. The separationchamber 944 b may also function as the transport region for transportingthe stacked body from the vapor-phase lubrication process chamber (orfirst process chamber) 944 a to the vapor-phase lubrication processchamber (or second process chamber) 944 c.

A substrate output robot 946 for outputting the stacked body formed withthe lubricant layer may be provided adjacent to the airlock chamber 945via a gate valve G8. The substrate output robot 946 is an example of thetransport apparatus. A transport cassette 948 configured to transport aplurality of stacked bodies (for example, 50 stacked bodies) may betransported amongst each of the chambers 943 through 945, and 947. Thetransport cassette 948 is an example of a transport means. A gassupplying means (or gas supplying part), an exhaust means (or exhaustpart), and the like may be provided with respect to each of the chamberswithin the vapor-phase lubrication deposition apparatus 102, ifnecessary.

In each embodiment, the process gas pressure A within the vapor-phaselubrication process chamber (hereinafter also referred to as “firstprocess chamber”) 944 a, the process gas pressure B within thevapor-phase lubrication process chamber (hereinafter also referred to as“second process chamber”) 944 c, and the gas pressure C within theseparation chamber 944 b in the transport region may preferably satisfythe relationships C>A and C>B. According to this configuration, theprocess gas within the first process chamber 944 a and the process gaswithin the second process chamber 944 c can be prevented from mixing.Hence, the first lubricant layer made solely of the first lubricant andhaving a high coverage and a high bond with respect to the protectionlayer can be formed within the first process chamber 944 a. Thereafter,only the second lubricant is deposited within the second process chamber944 c. As a result, it is possible to form a lubricant layer includingsuitable amounts of the bond layer and the free layer.

In each embodiment, the gas supplied to the transport region, that is,the separation chamber 944 b, may preferably be an inert gas. Studiesconducted by the present inventors confirmed that the inert gasintroduces virtually no effects on the lubricant layer that is formed,even when the inert gas mixes into the process gas within the firstprocess chamber 944 a or into the process gas within the second processchamber 944 c.

In addition, each embodiment may preferably set a process gas pressure Dat the time of the deposition of the protection layer and a gas pressureE in the transport path of the stacked body after the formation of theprotection layer up to the first process chamber 944 a to satisfyrelationships E>D and E>A, in order to prevent the quality of theprotection layer and the lubricant layer from deteriorating due tomixing of the process gas used to deposit the protection layer and theprocess gas used to form the bond layer from the first lubricant.

Each embodiment sets the process gas pressure D within a range of 1 Pato 20 Pa, the process gas pressures A and B within a range of 1 Pa to 50Pa, and the gas pressures C and E within a range of 10 Pa to 500 Pa, forexample, and preferably satisfies the relationships C>A, C>B, E>D, andE>A. The effect of preventing mixing of the process gases increases asthe pressure difference between each of the process gas pressures A, B,and D and the each of the gas pressures C and E becomes larger. However,when the pressure difference is excessively large, the effect of theinert gas flowing into each process gas increases, and the filmthickness distribution of the protection layer and the lubricant layermay deteriorate. For this reason, the pressure difference between eachof the process gas pressures A, B, and D and the each of the gaspressures C and E may preferably be 150 Pa or less.

The stacked bodies (hereinafter also referred to as “substrates”) withinthe vapor-phase lubrication deposition apparatus 102 may move so thatthe following processes are repeated, and processes including thefollowing steps s21 through s45 may be performed continuously.

Step s21: The gate valves G5 and G6 are closed.

Step s22: The inside of the isolation chamber 943 is decompressed tovacuum.

Step s23: The gate valve G5 is opened.

Step s24: The substrates (for example, 50 substrates) within the airlockchamber 12 are inserted into the transport cassette 948 within theisolation chamber 943 using the vacuum robot 941.

Step s25: The gate valve G5 is closed.

Step s26: An inert gas is supplied into the isolation chamber 943 togenerate the gas pressure (or internal pressure) E.

Step s27: The gate valve G6 is opened.

Step s28: The transport cassette 948 within the isolation chamber 943 issupplied into the first process chamber 944 a. In this state, the firstprocess chamber 944 a has the process gas pressure A inside thereof.

Step s29: After supplying the transport cassette 948 into the firstprocess chamber 944 a, the gate valve G6 is closed.

Step s30: The first lubricant layer is formed on the stacked body withinthe transport cassette 948 within the first process chamber 944 a.

Step s31: The gate valve G11 is opened. In this state, an inert gas issupplied into the separation chamber 944 b to generate the gas pressure(or internal pressure) C.

Step s32: The transport cassette 948 accommodating the stacked bodyhaving the first lubricant layer formed thereon is moved into theseparation chamber 944 b. In this state, the gate valve G11 is closed,and the gate valve G12 is opened.

Step s33: The transport cassette 948 within the separation chamber 944 bis supplied into the second process chamber 944 c. In this state, thesecond process chamber 944 c has the process gas pressure B insidethereof.

Step s34: After supplying the transport cassette 948 into the secondprocess chamber 944 c, the gate valve G12 is closed.

Step s35: The second lubricant layer is formed on the stacked bodywithin the transport cassette 948 within the second process chamber 944c.

Step s36: The gate valve G7 is opened, and the transport cassette 948accommodating the stacked body having the first and second lubricantlayers formed thereon is moved to the airlock chamber 945.

Step s37: The gate valve G7 is closed.

Step s38: The inside of the airlock chamber 945 is set to atmosphericpressure.

Step s39: The gate valve G8 is opened.

Step s40: The stacked body subjected to the process is extracted by thesubstrate output robot 946.

Step s41: The gate valve G8 is closed.

Step s42: The inside of the airlock chamber 945 is decompressed tovacuum.

Step s43: The gate valve G9 is opened.

Step s44: The empty transport cassette 948 is moved to the isolationchamber 943 via the return path chamber 947. The inside of the returnpath chamber 947 is decompressed to vacuum.

Step s45: The gate valve G10 is opened in the decompression state of theisolation chamber 943, and the empty transport cassette 948 is suppliedinto the isolation chamber 943.

FIG. 2 is a cross sectional view illustrating an example of a magneticrecording medium 1 fabricated by the fabrication apparatus illustratedin FIG. 1. The data recording system with respect to the magneticrecording medium 1 may be an in-plane (or longitudinal) recording systemor a perpendicular recording system, however, it is assumed for the sakeof convenience that the magnetic recording medium 1 fabricated in eachembodiment employs the perpendicular recording system.

The magnetic recording medium 1 may include a substrate 100, a bondinglayer 110 formed on the substrate 100, a soft magnetic underlayer 120formed on the bonding layer 110, an orientation control layer 130 formedon the soft magnetic underlayer 120, a nonmagnetic underlayer 140 formedon the orientation control layer 130, a perpendicular recording layer150 formed on the nonmagnetic underlayer 140, a protection layer 160formed on the perpendicular recording layer 150, and a lubricant layer170 formed on the protection layer 160. The perpendicular recordinglayer 150 is an example of a magnetic recording layer. In this example,the magnetic recording medium 1 has a configuration in which the bondinglayer 110, the soft magnetic underlayer 120, the orientation controllayer 130, the nonmagnetic underlayer 140, the perpendicular recordinglayer 150, the protection layer 160, and the lubricant layer 170 areformed on both sides of the substrate 100. In FIG. 2, a stackedstructure in which the bonding layer 110 up to the protection layer 160are stacked on both sides of the substrate 100, that is, the stackedstructure in which all of the layers of the magnetic recording medium 1except the lubricant layer 170 are formed on both sides of the substrate100, forms a stacked body 180. Further, in FIG. 2, a stacked structurein which the bonding layer 110 up to the perpendicular recording layer150 are stacked on both sides of the substrate 100, that is, the stackedstructure in which all of the layers of the magnetic recording medium 1except the protection layer 160 and the lubricant layer 170 are formedon both sides of the substrate 100, forms a stacked body 190.

In this example, the substrate 100 may be made of a nonmagneticmaterial. For example, the substrate 100 may be formed by a metalsubstrate made of a metal material such as aluminum, aluminum alloy, andthe like. For example, the substrate 100 may be formed by a nonmetallicsubstrate made of a nonmetallic material such as glass, ceramics,silicon, silicon carbide, carbon, and the like. In addition, thesubstrate 100 may have a NiP layer or a NiP alloy layer, formed on thesurface of the metal substrate or the nonmetallic substrate, by plating,sputtering, or the like.

For example, the glass substrate may also be made of float glass, glassceramics, and the like. For example, general-purpose soda-lime glass,aluminosilicate glass, and the like may be used for the flat glass. Inaddition, lithium glass ceramics, and the like, for example, may be usedfor the glass ceramics. Further, a sintered body having general-purposealuminum oxide, aluminum nitride, silicon nitride, or the like as itsmain component, or a fiber reinforced material of such materials, forexample, may be used for the ceramic substrate.

Corrosion of the substrate 100 may progress due to the effects ofadsorbed gas or moisture on the surface, diffusion of the substratecomponent, and the like when the substrate 100 makes contact with thesoft magnetic underlayer 120 having Co or Fe as its main component aswill be described later. For this reason, the bonding layer 110 maypreferably be provided between the substrate 100 and the soft magneticunderlayer 120. The material used for the bonding layer 110 may suitablybe selected from Cr, Cr alloy, Ti, Ti alloy, and the like, for example.The bonding layer 110 may preferably have a thickness of 2 nm (20 Å) orgreater.

The soft magnetic underlayer 120 may be provided to reduce noise at thetime of recording and reproduction, in a case in which the perpendicularrecording system is employed. In this example, the soft magneticunderlayer 120 may include a first soft magnetic layer 121 formed on thebonding layer 110, a spacer layer 122 formed on the first soft magneticlayer 121, and a second soft magnetic layer 123 formed on the spacerlayer 122. In other words, the soft magnetic underlayer 120 may have astructure in which the spacer layer 122 is sandwiched between the firstsoft magnetic layer 121 and the second soft magnetic layer 123.

The first soft magnetic layer 121 and the second soft magnetic layer 123may preferably be made of a material including Fe:Co in a range of 40:60to 70:30 in atomic ratio (at %). In order to improve the permeabilityand corrosion resistance, the first soft magnetic layer 121 and thesecond soft magnetic layer 123 may preferably include an elementselected from a group consisting of Ta, Nb, Zr, and Cr in a range of 1at % to 8 at %. In addition, the spacer layer 122 may be made of Ru, Re,Cu, or the like, and may preferably be made of Ru in particular.

The orientation control layer 130 may be provided to improve therecording and reproducing characteristics, by reducing crystal grainsizes of the perpendicular recording layer 150 that is formed via thenonmagnetic underlayer 140. The material used for the orientationcontrol layer 130 is not limited to a particular material, however, amaterial having a hcp structure, a fcc structure, or an amorphousstructure may preferably be used for the orientation control layer 130.The orientation control layer 130 may preferably be made of an Ru alloy,Ni alloy, Co alloy, Pt alloy, or Cu alloy in particular, and theorientation control layer 130 may have a multi-layer structure in whichsuch alloys are stacked. For example, a multi-layer structure formed byNi alloy and Ru alloy, a multi-layer structure formed by Co alloy and Rualloy, or a multi-layer structure formed by Pt alloy and Ru alloy, maypreferably be formed from the side of the substrate 100.

The nonmagnetic underlayer 140 may be provided to suppress disturbancein crystal growth at an initial stacked part of the perpendicularrecording layer 150 that is stacked on the nonmagnetic underlayer 140,and to suppress noise generation at the time of the recording andreproduction. However, the nonmagnetic underlayer 140 may be omitted.

In this example, the nonmagnetic underlayer 140 may preferably be madeof a material including a metal having Co as its main component, andadditionally including an oxide. A Cr-content of the nonmagneticunderlayer 140 may preferably be in a range of 25 at % to 50 at %. Forexample, the oxide included in the nonmagnetic underlayer 140 maypreferably be an oxide of Cr, Si, Ta, Al, Ti, Mg, Co, or the like. TiO₂,Cr₂O₃, SiO₂, or the like may particularly be preferable for use as theoxide included in the nonmagnetic underlayer 140. The oxide-content ofthe nonmagnetic underlayer 140 may preferably be in a range of 3 mol %to 18 mol %, with respect to a mol total calculated by regarding analloy of Co, Cr, Pt, or the like, for example, forming the magneticgrains (or particles), as one compound.

In this example, the perpendicular recording layer 150 may include afirst magnetic layer 151 formed on the nonmagnetic underlayer 140, afirst nonmagnetic layer 152 formed on the first magnetic layer 151, asecond magnetic layer 153 formed on the first nonmagnetic layer 152, asecond nonmagnetic layer 154 formed on the second magnetic layer 153,and a third magnetic layer 155 formed on the second nonmagnetic layer154. In other words, in the perpendicular recording layer 150, the firstnonmagnetic layer 152 is sandwiched between the first magnetic layer 151and the second magnetic layer 153, and the second nonmagnetic layer 154is sandwiched between the second magnetic layer 153 and the thirdmagnetic layer 155.

The first magnetic layer 151, the second magnetic layer 153, and thethird magnetic layer 155 may be provided to store data by inverting themagnetization direction in a direction taken along the thickness of theperpendicular recording layer 150 by the magnetic energy supplied from amagnetic head 3 (illustrated in FIG. 3 which will be described later)and maintaining the state of the magnetization. The first magnetic layer151, the second magnetic layer 153, and the third magnetic layer 155 mayform the magnetic layer of this example.

The first magnetic layer 151, the second magnetic layer 153, and thethird magnetic layer 155 may preferably include metal magnetic grainshaving Co as its main component, and a nonmagnetic oxide, and have agranular structure in which the magnetic grains are surrounded by theoxide.

For example, the oxide included in the first magnetic layer 151, thesecond magnetic layer 153, and the third magnetic layer 155 maypreferably be Cr, Si, Ta, Al, Ti, Mg, Co, or the like. TiO₂, Cr₂O₃,SiO₂, or the like may particularly be preferable for use as the oxideincluded in the first magnetic layer 151, the second magnetic layer 153,and the third magnetic layer 155. In addition, the lowermost firstmagnetic layer 151 of the perpendicular recording layer 150 maypreferably include a complex (or composite) oxide made up of two or morekinds of oxides. The complex oxide included in the first magnetic layer151 may preferably be Cr₂O₃—SiO₂, Cr₂O₃—TiO₂, Cr₂O₃—SiO₂—TiO₂, or thelike.

In addition, the material used for the magnetic grains of the firstmagnetic layer 151, the second magnetic layer 153, and the thirdmagnetic layer 155 may preferably include compositions such as90(Co14Cr18Pt)-10(SiO₂) {mol concentration of 90 mol % calculated usingmagnetic particles having a Cr-content of 14 at %, a Pt-content of 18 at%, and the remainder Co as one compound, and 10 mol % of an oxidecomponent having SiO₂}, 92(Co10Cr16Pt)-8(SiO₂),94(Co8Cr14Pt4Nb)-6(Cr₂O₃), (CoCrPt)—(Ta₂O₅), (CoCrPt)—(Cr₂O₃)—(TiO₂),(CoCrPt)—(Cr₂O₃)—(SiO₂), (CoCrPt)—(Cr₂O₃)—(SiO₂)—(TiO₂),(CoCrPtMo)—(Ti), (CoCrPtW)—(TiO₂), (CoCrPtB)—(Al₂O₃),(CoCrPtTaNd)—(MgO), (CoCrPtBCu)—(Y₂O₃), (CoCrPtRu)—(SiO₂), and the like.

The first nonmagnetic layer 152 and the second nonmagnetic layer 154 maybe provided to facilitate the magnetic inversion in each of the magneticlayers, namely, the first magnetic layer 151, the second magnetic layer153, and the third magnetic layer 155 forming the perpendicularrecording layer 150, and to reduce noise by reducing variance of themagnetic inversions of the magnetic particles as a whole. In thisexample, the first nonmagnetic layer 152 and the second nonmagneticlayer 154 may preferably include Ru and Co, for example.

In the example illustrated in FIG. 2, the perpendicular recording layer150 includes magnetic layers (first, second, and third magnetic layers151, 153, and 155) forming the 3-layer structure, however, the structureof the magnetic layers is not limited to the 3-layer structure, and themagnetic layers may form a multi-layer structure of four (4) or morelayers. In addition, although a nonmagnetic layer (a corresponding oneof first and second nonmagnetic layers 152 and 154) is interposedbetween two adjacent magnetic layers (two adjacent ones of first,second, and third magnetic layers 151, 153, and 155) forming theperpendicular recording layer 150, the structure of the magnetic layersforming the perpendicular recording layer 150 is not limited to such astructure. For example, the perpendicular recording layer 150 may have astructure in which two magnetic layers having mutually differentcompositions are stacked.

The protection layer 160 may be provided to prevent corrosion of theperpendicular recording layer 150, and to prevent damage to the mediumsurface or the magnetic head 3 itself when the magnetic head 3 and themagnetic recording medium 1 make contact. The protection layer 160 maybe provided to also improve the corrosion resistance of the magneticrecording medium 1.

The protection layer 160 may be made of a known material. The protectionlayer 160 may be made of a material including C, SiO₂, ZrO₂, or SiC, forexample. In order to make the bonded ratio between the protection layer160 and the lubricant layer 170 controllable in a vicinity of 100%before the nitrogen atoms or the oxygen atoms are injected onto thesurface of the protection layer 160 or before nitriding or oxidizing thesurface of the protection layer 160, the protection layer may preferablybe made of pure carbon. In addition, from the standpoint of maintainingthe hardness of the protection layer 160 and making the protection layer160 relatively thin while controlling the bonded ratio in the vicinityof 100% between the protection layer 160 and the lubricant layer 170,the protection layer 160 may preferably be made of amorphous hard carbonor DLC (Diamond Like Carbon). Furthermore, from the standpoint ofrealizing a high recording density, the protection layer 160 maypreferably have a thickness of 1 nm to 10 nm, for example, in order toreduce the distance between the magnetic head 3 and the magneticrecording medium 1 in a magnetic storage apparatus, which will bedescribed later in conjunction with FIG. 3.

The lubricant layer 170 may be provided to suppress friction between themagnetic head 3 and the surface of the magnetic recording medium 1 whenthe magnetic head 3 makes contact with the magnetic recording medium 1,and to improve the corrosion resistance of the magnetic recording medium1. From the standpoint of realizing a high recording density, thelubricant layer 170 may preferably have a thickness of 1 nm to 2 nm, forexample, in order to reduce the distance between the magnetic head 3 andthe magnetic recording medium 1 in the magnetic storage apparatus, whichwill be described later in conjunction with FIG. 3.

When forming the lubricant layer 170 by the vapor-phase lubrication, thelubricant is heated to a temperature in a range of 90° C. to 150° C.,and vapor of the lubricant is introduced into the reaction chamber. Thepressure within the reaction chamber is set to approximately 10 Pa, forexample, and an exposure time of the stacked body in the reactionchamber is set to approximately 10 seconds, for example, in order toform the lubricant layer 170 on the surface of the protection layer 160to a thickness of approximately 1 nm, for example.

FIG. 3 is a perspective view illustrating an example of a configurationof the magnetic storage apparatus having the magnetic recording medium 1fabricated in this embodiment of the present invention.

A magnetic storage apparatus 50 illustrated in FIG. 3 may be providedwith the magnetic recording medium 1 that magnetically records data, arotary driving part 2 that rotationally drives the magnetic recordingmedium 1, the magnetic head 3 that writes (or records) data to and reads(or reproduces) the data from the magnetic recording medium 1, acarriage 4 mounted with the magnetic head 3 (or head slider), a headdriving part 5 that moves the magnetic head 3 via the carriage 4relative to the magnetic recording medium 1, and a signal processor 6.The signal processor 6 may subject data input from an external host unit(not illustrated) or the like to a known signal processing, in order tosupply recording signals suited for the recording on the magneticrecording medium 1 to the magnetic head 3. The signal processor 6 maysubject the signals read from the magnetic recording medium 1 by themagnetic head 3 to a known signal processing, and output reproduced datato the external host unit or the like.

In the example illustrated in FIG. 3, the magnetic recording medium 1 isa magnetic disk having a disk shape. The magnetic disk includes amagnetic recording layer to record the data, on at least one of the twosides (or surfaces) of the magnetic disk. The magnetic recording layermay be provided on both sides (or both surfaces) of the magnetic disk,as illustrated in FIG. 2. Further, in the example illustrated in FIG. 3,a plurality of magnetic recording media (in this example, three (3)magnetic recording media) are provided in the magnetic storage apparatus50. However, the number of magnetic recording media 1 provided in themagnetic storage apparatus 50 may be one (1) or greater.

According to each embodiment described above, the bonded ratio of thelubricant layer that is formed is high and falls within a suitable rangewith respect to the surface of the protection layer, and the lubricantlayer that is formed includes a suitable free layer. In addition, thelubricant layer has a high coverage with respect to the surface of theprotection layer. In other words, each embodiment provides a magneticrecording medium fabrication method that can obtain a low coefficient offriction of the lubricant layer and a high coverage of the surface ofthe protection layer by the lubricant layer. For this reason, a magneticrecording medium having a high reliability and a high corrosionresistance can be obtained, and the reliability of the magnetic storageapparatus can be improved.

Further, the present invention is not limited to the embodiment, butvarious variations and modifications may be made without departing fromthe scope of the present invention.

First Practical Example PE1

Next, a description will be given of a practical example PE1 in which amagnetic recording medium is fabricated by the following fabricationmethod. More particularly, the magnetic recording medium is fabricatedusing the fabrication apparatus illustrated in FIG. 1. First, a cleanedglass substrate (manufactured by Konica Minolta, Inc. and having anouter diameter of 2.5 inches) is accommodated within the airlock chamber12 of the fabrication apparatus illustrated in FIG. 1, and thereafterplaced into the carrier 925 using the vacuum robot 111, in order to formstacked layers on the substrate surface. The inside of the depositionchambers are decompressed (or evacuated) to a vacuum (or base pressure)of 1×10⁻⁵ Pa.

Next, a bonding layer having a thickness of 10 nm is deposited on theglass substrate within the process chamber 905 in which the argon gaspressure is 1 Pa, using a 60Cr-50Ti target. In addition, a first softmagnetic layer having a thickness of 34 nm is deposited on the bondinglayer within the process chamber 906 in which the argon gas pressure is1 Pa and the substrate temperature is 100° C. or lower, using a46Fe-46Co-5Zr-3B {Fe-content of 46 at %, Co-content of 46 at %,Zr-content of 5 at %, and B-content of 3 at %} target. In addition, anRu layer having a thickness of 0.76 nm is deposited on the first softmagnetic layer within the process chamber 908, using an Ru target.Further, a second soft magnetic layer having a thickness of 34 nm isdeposited on the Ru layer within the process chamber 909, using a46Fe-46Co-5Zr-3B target. The first and second soft magnetic layerssandwiching the Ru layer are formed as the soft magnetic underlayer.

Next, a first underlayer having a thickness of 5 nm is deposited on thesoft magnetic underlayer within the process chamber 910 in which theargon gas pressure is 1 Pa, using a Ni-6W {W-content of 6 at %, and theremainder Ni} target. A second underlayer having a thickness of 10 nm isdeposited on the first underlayer within the process chamber 911, usingan Ru target. A third underlayer having a thickness of 10 nm isdeposited within the process chamber 912 in which the argon gas pressureis 8 Pa, using an Ru target. An underlayer having a 3-layer structure isformed by the first, second, and third underlayers.

Next, a magnetic layer having a multi-layer structure is deposited onthe underlayer having the 3-layer structure. More particularly, a91(72Co6Cr16Pt6Ru)-4SiO₂-3Cr₂O₃-2TiO₂ layer having a thickness of 6 nmis deposited on the third underlayer within the process chamber 913 inwhich the argon gas pressure is 1 Pa. In addition, a91(65Co12Cr13Pt10Ru)-4SiO₂-3Cr₂O₃-2TiO₂ layer having a thickness of 6 nmis deposited on the 91(72Co6Cr16Pt6Ru)-4SiO₂-3Cr₂O₃-2TiO₂ layer withinthe process chamber 915 in which the argon gas pressure is 1 Pa.Further, a 63Co15Cr16Pt6B layer having a thickness of 3 nm is depositedon the 91(65Co12Cr13Pt10Ru)-4SiO₂-3Cr₂O₃-2TiO₂ layer within the processchamber 916 in which the argon gas pressure is 1 Pa.

Next, a carbon protection layer having a thickness of 2.5 nm isdeposited on the magnetic layer within the process chambers 918 and 919,using an ion beam, in order to obtain the stacked body (or magneticrecording medium). The base pressure within the process chambers 918 and919 is 1×10⁻⁵ Pa, a mixture gas in which 4% methane is mixed to hydrogengas is used for the process gas, and the process gas pressure (D) is 8Pa. The chambers 920 and 921 are used as auxiliary chambers, and noprocess gas is supplied to the auxiliary chambers, and the base pressurewithin the auxiliary chambers is 1×10⁻⁵ Pa.

The stacked body that is obtained is removed from the carrier 925 by thevacuum robot 112, and is supplied into the vapor-phase lubricationdeposition apparatus 102 via the airlock chamber 13 by the vacuum robot941. The base pressure within the isolation chamber 943, the firstprocess chamber 944 a, the second process chamber 944 c, the airlockchamber 945, and the return path chamber 947 is set to 1×10⁻⁵ Pa. Inaddition, argon gas is supplied into the isolation chamber 943 (processgas pressure: D) so that the pressure within the isolation chamber 943becomes constant at 50 Pa, argon gas is supplied into the separationchamber 944 b at 50 Pa (gas pressure: C), a mixture gas containing 1:1(mass) of tetraol (Fomblin Z-TETRAOL (product name) manufactured bySolvay Solexis, Inc., molecular mass: 1800, heating temperature: 110°C.) gas represented by the following generalized formula (7) and alubricant (A20H-DD (product name) manufactured by MORESCO Corporation,molecular mass: 1800, heating temperature: 110° C.) gas represented bythe following generalized formula (8) is supplied into the first processchamber 944 a at 20 Pa (process gas pressure: A), and diol (molecularmass: 3000, heating temperature: 110° C.) gas is supplied into thesecond process chamber 944 c at 10 Pa (process gas pressure: B), and noprocess gas is supplied to the airlock chamber 945 and the return pathchamber 947. A lubricant layer having a thickness of 17 Δ is formed onthe stacked body by the vapor-phase lubrication deposition apparatus102.

In the generalized formula (7) above, p and q denote integers, and thenumber average molecular mass is 1800.

The A20H-DD is a compound in which x is 4, R₁ is CF₃, and R₂ is asubstituent of an end group —CH(OH)CH₂OH in the generalized formula (8)described above.

The stacked body having the first lubricant formed thereon by thevapor-phase lubrication deposition is transported outside thefabrication apparatus using the substrate output robot 946.

First Comparison Example CE1

The magnetic recording medium in a first comparison example CE1 isfabricated similarly to the first practical example PE1. However, in thefirst comparison example CE1, no second lubricant is deposited, and thelubricant layer is formed solely of the first lubricant. The thicknessof the lubricant layer is 17 Å.

Second Comparison Example CE2

The magnetic recording medium in a second comparison example CE2 isfabricated similarly to the first practical example PE1. However, in thesecond comparison example CE2, no first lubricant is deposited, and thelubricant layer is formed solely of the second lubricant. The thicknessof the lubricant layer is 17 Δ.

Second Practical Example PE2

In a second practical example PE2, after forming the carbon protectionlayer and before depositing the first lubricant, nitrogen ions areinjected onto the carbon protection layer in order to carry outnitriding of the surface of the carbon protection layer. Moreparticular, the ion beam is generated using a mixture gas of 40 sccm ofnitrogen gas and 20 sccm of neon gas. The amount of ions is 5.5×10¹⁵atoms/cm², the voltage of a positive electrode is +1500 V, the voltageof a negative electrode is −1500 V, the irradiation time is 10 seconds,and the injection depth into the carbon protection layer is 1.5 nm. Theconcentration of the nitrogen atoms at the surface of the carbonprotection layer is approximately 15 atomic percent (at. %).

Other conditions for the second practical example PE2 are the same asthose when fabricating the magnetic recording medium in the firstpractical example PE1 described above.

Third Practical Example PE3

The magnetic recording medium in a third practical example PE3 isfabricated similarly to the second practical example PE2 describedabove. However, in the third practical example PE3, diol (molecularmass: 3000) is used as the first lubricant, and a mixture containing 1:1(mass) of tetraol (molecular mass: 1800, Fomblin Z-TETRAOL (productname) manufactured by Solvay Solexis, Inc.) represented by the followinggeneralized formula (9) and A20H-DD (molecular mass: 1800) is used forthe second lubricant.HOCH₂CH(OH)—CH₂OCH₂CF₂O—(C₂F₄O)_(r)—(CF₂O)_(s)—CF₂CH₂OCH₂—CH(OH)CH₂OH  (9)

(Evaluation of Bonded Ratio of Lubricant Layer)

The bonded ratios of the magnetic recording media in the first throughthird practical examples PE1 through PE3 and the first and secondcomparison examples CE1 and CE2 are measured. The bonded ratio ismeasured by dipping the magnetic recording medium formed with thelubricant layer in a fluorocarbon solvent for five (5) minutes, andmeasuring the absorbance in a vicinity of 1270 cm⁻¹ at the same positionon the same medium before and after the dipping using ESCA. The bondedratio is defined as a percentage of the ratio of the absorbances beforeand after the dipping, that is, by [{(Absorbance AfterDipping)/(Absorbance Before Dipping)}×100]. Vertrel XF (manufactured byDu Pont-Mitsui Fluorochemicals Co., Ltd.) is used for the fluorocarbonsolvent. Evaluation results of the bonded ratios are illustrated inTable 1.

TABLE 1 Bonded Ratio Si Adsorption Lubrication (%) Number Pickup PE1 854 No CE1 80 4 Yes CE2 80 95 No PE2 85 3 No PE3 87 4 No

(Coverage Evaluation (Si Adsorption Number) of Lubricant)

The coverage of the lubricant layer of the magnetic recording media inthe first through third practical examples PE1 through PE3 and the firstand second comparison examples CE1 and CE2 are evaluated according tothe following method. The method of evaluating the coverage describedhereunder indirectly evaluates the coverage of the lubricant layer atthe surface of the magnetic recording medium, by checking contaminationof the magnetic recording medium caused by an environmental substancethat generates a contamination substance under a high temperatureenvironment. In other words, if the coverage of the lubricant layer ishigh at the surface of the magnetic recording medium, the magneticrecording medium is uneasily contaminated by the environmentalsubstance.

In the evaluation of the coverage described hereunder, Si ions are usedas the environmental substance that generates the contaminationsubstance under the high temperature environment, and an Si adsorptionnumber is measured as the amount of the contamination substance that isgenerated by the environmental substance and is contaminating themagnetic recording medium.

More particularly, the magnetic recording medium that is the evaluationtarget is first held in a high temperature environment in which thetemperature is 85° C. and the humidity is 0% for 240 hours underexistence of siloxane Si rubber.

Next, the Si adsorption number at the surface of the magnetic recordingmedium is analyzed and measured using tof-SIMS (time of flight-SecondaryIon Mass Spectrometry), and the extent of the contamination caused bythe Si ions, that is, the environmental substance, under the hightemperature environment, is evaluated. Evaluation results of the Siadsorption numbers are illustrated in Table 1 above. The higher the Siadsorption number, the more easily the magnetic recording medium iscontaminated and the more deteriorated (or the lower) the coverage ofthe surface of the protection layer is by the lubricant layer.

The evaluation of the Si adsorption number is made by setting the extentof the Si ion contamination for a reference disk to one (1), where thereference disk is not subjected to a high-temperature process and isformed with a lubricant layer made of Fomblin Z-TETRAOL (product name,manufactured by Solvay Solexis, Inc.) and having a thickness of 17 Å onthe stacked body having each of the layers up to the protection layerformed on the nonmagnetic substrate.

(Evaluation of Lubrication Pickup)

The lubricant pickup of the magnetic recording media in the firstthrough third practical examples PE1 through PE3 and the first andsecond comparison examples CE1 and CE2 are evaluated, by making the headslider seek on the surface of the magnetic recording media for a longtime, and confirming the existence of the lubricant adhered on the headslider by a light microscope. More particularly, the magnetic recordingmedia are rotated at 1000 rpm which is lower than the regular rotationalspeed, and the head slider is made to seek on the surface of themagnetic recording media. The seek velocity is 2 Hz, and the seek timeis 24 hours. The existence of the lubricant adhered on the head slideris confirmed using a DIC (Differential Interference Contrast) microscopewith a magnification of 600 times. The evaluation results of thelubricant pickup is illustrated in Table 1 above.

It may be confirmed from Table 1 that the bonded ratios of the first andsecond comparison examples CE1 and CE2 are both 80%, however, thelubricant pickup exists in the first comparison example CE1, and thecoverage of the surface of the protection layer by the lubricant layeris low in the second comparison example CE2. On the other hand, it maybe confirmed from Table 1 that the bonded ratios of the first throughthird practical examples PE1 through PE3 are 85% to 87%, the coverage ofthe surface of the protection layer by the lubricant layer issatisfactory, and the lubricant pickup does not exist or is negligible.Therefore, it may be confirmed that, according to the first throughthird practical examples PE1 through PE3, the coverage of the surface ofthe protection layer by the lubricant layer is within a suitable rangeand high, the lubricant pickup is suppressed although a suitable freelayer is included in the lubricant layer, and the coverage of thesurface of the protection layer by the lubricant layer is high.

According to the embodiments and practical examples described above, alow coefficient of friction of the lubricant layer and a high coverageof the surface of the protection layer by the lubricant layer can beobtained simultaneously.

Further, the present invention is not limited to these practicalexamples, but various variations and modifications may be made withoutdeparting from the scope of the present invention.

What is claimed is:
 1. A method of fabricating a magnetic recordingmedium by sequentially forming a magnetic recording layer, a protectionlayer, and a lubricant layer on a stacked body, comprising: forming thelubricant layer, wherein the forming the lubricant layer includesdepositing a first lubricant on the stacked body after forming theprotection layer, to form a first lubricant layer by vapor-phaselubrication deposition, without exposing the stacked body to atmosphere;and depositing a second lubricant on the first lubricant layer of thestacked body after depositing the first lubricant, to form a secondlubricant layer by vapor-phase lubrication deposition, without exposingthe stacked body to atmosphere, wherein the first lubricant has amolecular mass lower than a molecular mass of the second lubricant sothat the first lubricant layer has a molecular mass lower than amolecular mass of the second lubricant layer, and wherein the firstlubricant has a chemical polarity higher than a chemical polarity of thesecond lubricant so that the first lubricant layer has a chemicalpolarity higher than a chemical polarity of the second lubricant layer.2. The method of fabricating the magnetic recording medium as claimed inclaim 1, wherein the first lubricant includes a tetraol having amolecular mass within a range of 500 to
 2000. 3. The method offabricating the magnetic recording medium as claimed in claim 1, whereinthe second lubricant includes a diol having a molecular mass within arange of 1500 to
 5000. 4. The method of fabricating the magneticrecording medium as claimed in claim 1, further comprising: subjecting asurface of the protection layer to nitriding or oxidizing after formingthe protection layer and before depositing the first lubricant.
 5. Themethod of fabricating the magnetic recording medium as claimed in claim1, wherein the protection layer, or a surface layer portion afterforming the protection layer, is formed by carbon nitride or carbonoxide.
 6. The method of fabricating the magnetic recording medium asclaimed in claim 1, wherein the depositing the first lubricant iscarried out within a first process chamber and the depositing the secondlubricant is carried out within a second process chamber, and furthercomprising: transporting the stacked body from the first process chamberto the second process chamber via a transport region, wherein a processgas pressure A within the first process chamber, a process gas pressureB within the second process chamber, and a gas pressure C in thetransport region satisfy relationships C>A and C>B.
 7. The method offabricating the magnetic recording medium as claimed in claim 6, furthercomprising: supplying an inert gas to the transport region.
 8. Themethod of fabricating the magnetic recording medium as claimed in claim1, wherein a bonded ratio between the protection layer and the firstlubricant layer is in a range of 60% to 90%, and a bonded ratio betweenthe protection layer and the second lubricant layer is in a range of 10%to 30%.
 9. The method of fabricating the magnetic recording medium asclaimed in claim 8, wherein a bonded ratio between the protection layerand the lubricant layer is in a range of 85% to 87%.
 10. The method offabricating the magnetic recording medium as claimed in claim 1, whereina bonded ratio between the protection layer and the lubricant layer isin a range of 85% to 87%.
 11. The method of fabricating the magneticrecording medium as claimed in claim 1, further comprising: subjecting asurface of the protection layer to oxidizing after forming theprotection layer and before depositing the first lubricant.
 12. Themethod of fabricating the magnetic recording medium as claimed in claim11, wherein the protection layer, or a surface layer portion afterforming the protection layer, is formed by carbon oxide.
 13. The methodof fabricating the magnetic recording medium as claimed in claim 1,wherein the protection layer, or a surface layer portion after formingthe protection layer, is formed by carbon oxide.